UAL Corp's United Airlines will ramp up its efforts to lure well-heeled business travelers by adding fully reclining seats to its international business-class cabins, the company said on Monday.

Major airlines like United and AMR Corp's American Airlines, battered by low-fare competition, have made many improvements to their business- and first-class cabins.

American was set to announce details of its Boeing Co. 777 refurbishment project on Monday.

United aims to complete its upgrade by late 2009. When the work is done, United will offer lie-flat seating in its first- and business-class cabins across its international fleet of 97 wide-body Boeing 767, 747 and 777 aircraft.

United, the second-largest U.S. carrier by passenger traffic, said it plans to invest hundreds of millions of dollars on the premium-class upgrades.

(Reporting by Chris Reiter and Kyle Peterson)